events: optimize condition for optimal scenario

Instead of always checking whether we've already warned about a
possible EventEmitter memory leak, first run the rest of the
code as accessing random properties on an Array is expensive.

In addition, remove an unnecessary truthy check.

PR-URL: https://github.com/nodejs/node/pull/20452


Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>